What is a centimetre?
A centimetre is a metric unit of length equal to one hundredth of a metre. It is commonly used for small everyday measurements.
A centimetre is a metric unit of length. There are exactly 100 centimetres in 1 metre, so 1 centimetre is 0.01 metres.
Centimetres are useful when metres feel too large and millimetres feel too detailed. They are common for body measurements, product sizes, furniture dimensions, clothing sizes, crafts and school maths.
Why centimetres matter
Centimetres are one of the most practical everyday metric units. They are small enough for short measurements but still easy to read without lots of decimals.
For example, a phone might be 15 cm tall, a book might be 21 cm wide, and a shelf might be 80 cm long.
Centimetre conversions
Here are the most common centimetre conversions used in everyday measurements.
| Conversion | Value | Example |
|---|---|---|
| 1 centimetre to millimetres | 10 mm | 12 cm = 120 mm |
| 1 centimetre to metres | 0.01 m | 175 cm = 1.75 m |
| 1 centimetre to inches | about 0.3937 in | 10 cm ≈ 3.94 in |
| 1 inch to centimetres | 2.54 cm | 6 in = 15.24 cm |
| 100 centimetres | 1 metre | 250 cm = 2.5 m |
Centimetre conversion formulas
Centimetre conversions use a simple conversion factor.
metres = centimetres ÷ 100
inches = centimetres ÷ 2.54
centimetres = inches × 2.54
Metric conversions such as centimetres to metres are exact. Conversions into inches often create decimals, so rounding may be needed for everyday use.
Centimetres vs metres
A centimetre is smaller than a metre. There are exactly 100 centimetres in 1 metre.
| Unit | Best for | Example |
|---|---|---|
| millimetres | very small measurements | screw size, card thickness, precise gaps |
| centimetres | small everyday lengths | phone size, book size, waist measurement |
| metres | larger everyday dimensions | room length, height, garden width |
Common UK examples
In the UK, centimetres are widely used for product dimensions, school work, clothing measurements, parcels, furniture, DIY and many online shopping measurements.
- Height: a person’s height may be written as 175 cm, 1.75 m, or 5 ft 9 in.
- Products: furniture, screens, books and boxes are often listed in centimetres.
- Clothing: waist, chest, sleeve and inseam measurements may use centimetres or inches.
- DIY: short measurements are often easier to read in centimetres than metres.
Centimetre conversion examples
| Question | Calculation | Answer |
|---|---|---|
| How many mm is 25 cm? | 25 × 10 | 250 mm |
| How many metres is 180 cm? | 180 ÷ 100 | 1.8 m |
| How many inches is 30 cm? | 30 ÷ 2.54 | about 11.81 in |
| How many cm is 12 inches? | 12 × 2.54 | 30.48 cm |
Rounding centimetre conversions
Centimetres to millimetres or metres are usually exact and easy to show. Centimetres to inches can produce long decimals, so rounding depends on the situation.
For casual measurements, one or two decimal places is usually enough. For cutting materials, fitting products or technical work, keep more precision and check the tolerance you need.
Quick answers
| Question | Answer |
|---|---|
| How many centimetres are in a metre? | 100 centimetres. |
| How many millimetres are in a centimetre? | 10 millimetres. |
| How many inches are in a centimetre? | About 0.3937 inches. |
| How many centimetres are in an inch? | Exactly 2.54 centimetres. |
FAQs
What is a centimetre used for?
A centimetre is used for small everyday measurements such as product dimensions, body measurements, clothing sizes, school maths, crafts and DIY.
Is a centimetre smaller than a metre?
Yes. One metre is equal to 100 centimetres, so a centimetre is one hundredth of a metre.
How do you convert centimetres to inches?
Divide centimetres by 2.54. For example, 30 cm ÷ 2.54 is about 11.81 inches.
How do you convert inches to centimetres?
Multiply inches by 2.54. For example, 12 inches × 2.54 = 30.48 cm.
Sources
Conversion values are based on standard metric and imperial relationships, including 100 centimetres in 1 metre, 10 millimetres in 1 centimetre and exactly 2.54 centimetres in 1 inch.